The present disclosure relates generally to supporting Layer 2 (L2) and Layer 3 (L3) virtual private networks (VPNs) over a Layer 2 or Layer 3 (L3) infrastructure.
Many applications in a Data Center network require L2 connectivity between all servers running an application. In order to provide the required L2 connectivity across an IP transport, enterprises have had to either dedicate fiber interconnects to a L2 extension or use pseudowire based technologies such as EoMPLS (Ethernet over Multiprotocol Label Switching) or VPLS (Virtual Private LAN Service). Others have opted for low performance IP based point-to-point solutions such as L2TPv3 (Layer 2 Tunneling Protocol Version 3) on software switched platforms. These conventional systems have a number of technical, operational, and cost drawbacks. For example, all of these systems result in a complex mesh of logical connections. Furthermore, this mesh usually creates forwarding and learning loops, which can only be broken by running Spanning Tree Protocol (STP) over the already complex logical mesh.
An alternative solution to provide Layer 3 VPNs is network virtualization. However, conventional methods for network virtualization do not work well in enterprise networks and typically lack the scalability and functionality for service provider networks. Many enterprises have considered MPLS IP-VPNs (IETF RFC 2547, “BGP/MPLS VPNs”, E. Rosen et al., March 1999) as one tool to implement network virtualization. This requires the introduction of MPLS into enterprise networks and relies heavily on tunnels.
Another drawback with conventional network virtualization is that the systems require multiple routing and forwarding tables to be maintained in every device in a path from a source node to a destination node. For example, “in-the-network” virtualization models intrinsic to VNETs (virtual networks) require all devices in the core to be configured, managed, and maintain state.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.